Smith declared Stern, her lawyer and boyfriend, executor of her estate in her will, which was drawn up in 2001.
When the document was drafted, Smith only had one child, Daniel, who died three days after Dannielynn was born last year.
The will states that "although she did not expect to have any children in the future, if she did, she wanted them to share equally in the trust created for Daniel."
Stern's petition said Smith did not update her will during the months between Daniel's death, Dannielynn's birth and her own death Feb. 8, TMZ.com reported Thursday.
Stern filed the papers to clarify the will, noting, "As a matter of law, Dannielynn is a pretermitted heir."
Although Marshall left much of his fortune to Smith in his will, his family contested the document and has battled Smith for years over the money.